Self-Adhesive Polyimide (PI)@Reduced Graphene Oxide (RGO)/PI@Carbon Nanotube (CNT) Hierarchically Porous Electrodes: Maximizing the Utilization of Electroactive Materials for Organic Li-Ion Batteries

Although organic carbonyl polymers have been successfully used as electrodes for lithium-ion batteries (LIBs), the operational capacity and energy density are still restricted due to their low utilization of active materials, poor electronic conductivity, and insulated binders. In this contribution, an efficient conductive network composed of reduced graphene oxide (RGO) and carbon nanotubes (CNTs) is introduced into polyimide (PI) via in-situ polymerization. Benefitting from the intrinsic viscosity of PI precursor, the self-adhesive PI@RGO/PI@CNT electrode can be obtained through imidization and thermal treatment without any insulated binders. Structural characterization reveals that PI uniformly grows on the RGO layer and connects with CNTs to form conductive networks, implying that a small amount of carbons can greatly improve the conductivity. As expected, the PI@RGO/PI@CNT electrode delivers a high initial capacity of 1291 mAh g⁻¹ at 0.1 A g⁻¹, an ultrahigh-rate performance of 212 mAh g⁻¹ at 5 A g⁻¹, and a stable cyclability with capacity retention of 96% at 10 A g⁻¹. Compared with reported PI-based electrodes, the PI@RGO/PI@CNTs electrode could achieve a superhigh utilization of active materials. This work proposes an effective method to improve the utilization of PI and provides a guideline on the electrode structural design and preparation process.